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1

The Development of a combined method to quicklyassess ship speed and fuel consumption at different powertrain load and sea conditions

Krata P., Kniat A., Guedes Soares C., Krata H.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2021

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Vol. 15 No. 2

437--445

EN

Decision support systems (DSS) recently have been increasingly in use during ships operation. They require realistic input data regarding different aspects of navigation. To address the optimal weather routing of a ship, which is one of the most promising field of DSS application, it is necessary to accurately predict an actually attainable speed of a ship and corresponding fuel consumption at given loading conditions and predicted weather conditions. In this paper, authors present a combined calculation method to predict those values. First, a deterministic modeling is applied and then an artificial neural network (ANN) is structured and trained to quickly mimic the calculations. The sensitivity of the ANN to adopted settings is analyzed as well. The research results confirm a more than satisfactory quality of reproduction of speed and fuel consumption data as the ANN response meet the calculation results with high accuracy. The ANN-based approach, however, requires a significantly shorter time of execution. The directions of future research are outlined.

2

Preliminary results of a system-theoretic assessment of maritime autonomous surface ships’ safety

Wróbel K., Krata P., Montewka J.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2019

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Vol. 13. no. 4

717--723

EN

While a system-theoretic approach to the safety analysis of innovative socio-technical systems gains a growing acceptance among academia, safety issues of Maritime Autonomous Surface Ships (MASS) remain largely unexplored. Therefore, we applied a System-Theoretic Process Analysis to develop and analyze a preliminary model of the unmanned shipping system in order to elaborate safety recommendations for future developers of the actual system. Results indicate that certain advancements shall be undertaken in relation to MASS’ software solutions in particular.

3

Multi-objective weather routing of sailboats considering wave resistance

Życzkowski M., Krata P., Szłapczyński R.

Polish Maritime Research

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2018

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nr 1

4--12

EN

The article presents a method to determine the route of a sailing vessel with the aid of deterministic algorithms. The method assumes that the area in which the route is to be determined is limited and the basic input data comprise the wind vector and the speed characteristic of the vessel. Compared to previous works of the authors, the present article additionally takes into account the effect of sea waves with the resultant resistance increase on the vessel speed. This approach brings the proposed model closer to real behaviour of a sailing vessel. The result returned by the method is the sailing route, optimised based on the multi-criteria objective function. Along with the time criterion, this function also takes into account comfort of voyage and the number of performed turns. The developed method has been implemented as simulation application SaillingAssistance and experimentally verified.

4

Ocena zapasu stateczności statków ro-ro w typowych stanach załadowania pod kątem unikania rezonansu kołysań bocznych

Krata P.

Zeszyty Naukowe Akademii Morskiej w Gdyni

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2016

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nr 97

99--110

PL

W artykule poruszono problem rezonansu kołysań bocznych statku jako istotnego czynnika wpływającego na bezpieczeństwo żeglugi. Wskazano na znaczenie parametrów statecznościowych statku w kontekście możliwości wystąpienia rezonansu. Następnie przedstawiono ocenę stateczności statków ro-ro w typowych eksploatacyjnych stanach załadowania pod kątem rozważanej możliwości intencjonalnego modyfikowania stateczności podczas rejsu, co ma prowadzić do wyjścia ze stref rezonansowych bez zmiany kursu lub prędkości statku lub zaledwie z niewielkimi zmianami. Pod uwagę wzięto zarówno wysokość metacentryczną statków ro-ro, jak i charakterystyki statecznościowe dla dużych kątów przechyłu, takie jak: wartość ramienia prostującego, kąt występowania maksimum krzywej Reeda i pole pod krzywą ramion prostujących. Wykazano, że w typowych stanach załadowania statki ro-ro mają wystarczający zapas stateczności, by jej modyfikacje mogły być użyte jako element unikania zagrożeń rezonansowych.

EN

In this paper ship’s synchronous rolling is considered, which is a significant factor influencing safety of navigation in rough sea conditions. The transverse stability characteristics are emphasized in terms of ship vulnerability to resonance rolling. Then an assessment of stability of Ro-Ro ships is carried out on the basis of collected data regarding their typical operational loading conditions. The feasibility of intended modification of stability characteristics of vessels underway is examined as a mean of the resonance zone exit instead of alternation of ship speed and course. The initial metacentric height is taken into account as well as the righting arm for large angles of heel. The dynamic stability represented by the area under the GZ curve is considered too. The research leads to the conclusion that Ro-Ro ships in their typical operational loading conditions reveal a massive stability margin allowing for the practical application of the proposed method. There is a room for modification of the stability characteristics to avoid synchronous rolling without excessive alternation of ship speed and course.

5

Towards the Development of a Risk Model for Unmanned Vessels Design and Operations

Wróbel K., Krata P., Montewka J., Hinz T.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2016

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Vol. 10, no. 2

267--274

EN

An unmanned merchant vessel seems to be escaping from the stage of idea exploration. Once the concept proofs its safety, it may become a part of maritime reality. Although the safety aspect of such a ship has been addressed by a handful of scholars, the problem remains open. This is mainly due to lack of knowledge regarding actual operational circumstances and design of unmanned ships, which are yet to be developed. In the attempt of bridging this gap, the risk analysis associated with unmanned ships needs to be carried out, where all relevant hazards and consequences are assessed and quantified in systematic manner. In this paper we present the results of a first step of such analysis, namely the hazard analysis associated with the unmanned ships. The list of hazards covers various aspects of unmanned shipping originating from both design and operational phases of vessel’s life. Subsequently the hazards and related consequences are organized in a casual manner, resulting in the development of a structure of a risk model.

6

Towards the assessment of critical area in a collision encounter accounting for stability conditions of a ship

Krata P., Montewka J., Hinz T.

Prace Naukowe Politechniki Warszawskiej. Transport

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2016

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z. 114

169--178

EN

The rules of road, called COLREGS provide guidelines for navigators onboard ships involved in collision encounter at navigable waters. Specific roles for stand-on and give-a-way vessels are assigned, depending on the phase of the encounter. In this paper we extend further our earlier work on the definition of the boundaries for the third phase of the encounter. The latter is referred to as critical area for an escape maneuver of a stand-on ship, in the situation where the give-way vessel does not take an action. This area is determined with the use of a state-of-the-art, six degree-of-freedom hydrodynamic model of ship motion. Series of simulations are conducted for a specific type of encountering ships applying various rudder angles to perform collision evasive maneuvers. Varying rudder angles reflect the fact, that hard-to-side command cannot always be executed, due to stability conditions of a ship. As a result we obtained a set of areas of various size, depending on the rudder angle used to perform evasive action for the predefined ship loading conditions related to her transverse stability characteristics. These demarcate the boundaries of the third phase of encounter for the standon ship, where other ships on collision courses must not enter. Otherwise a collision cannot be avoided by an action of one ship alone or the ship would have to turn too vigorously causing actual stability related threat.

PL

Prawidła prawa drogi dla statków nawigujących na morzu wynikające z konwencji COLREGS określają wzajemne obowiązki statków. W szczególności w sytuacji przecinania się kursów statków idącychn na zderzenie przypisywane są im obowiązki związane z ustąpieniem drogi oraz z utrzymaniem kursu i prędkości. Obowiązki te są jednak uzależnione od fazy spotkania. W artykule rozwinięte zostały wcześniejsze prace dotyczące określania krytycznego obszaru związanego z trzecią fazą spotkania, gdy statek uprzednio zobowiązany do utrzymania kursu i prędkości jest już zobligowany do podjęcia własnego manewru z powodu nie wykonania swego obowiązku przez statek zobowiązany do ustąpienia drogi. Kształt obszaru krytycznego wynika zarówno z rozmiarów statków, ich właściwości manewrowych, ale także z parametrów statecznościowych, co stanowi nowość w stosunku do dotychczasowego ujęcia zagadnienia. Wykorzystano zaawansowany hybrydowy model hydrodynamiczny określający w toku licznych symulacji ruch statku w sześciu stopniach swobody dla manewru antykolizyjnego wykonanego przy różnych wychyleniach steru. Nie zawsze bowiem wyłożenie steru na burtę jest dopuszczalne z punktu widzenia stateczności i wywoływanego przechyłu. W rezultacie wyznaczono granice obszaru krytycznego dla pełnego zakresu wychyleń steru. Niedopuszczalne jest zbliżenie powodujące wejście statku w obszar krytycznych, gdyż niemożliwe stanie się wówczas uniknięcie zderzenia własnym manewrem bądź przekroczona zostanie krytyczna wartość kąta przechyłu, co jest niebezpieczne dla statku, pasażerów i przewożonego ładunku.

7

Method for ship’s rolling period prediction with regard to non-linearity of GZ curve

Wawrzyński W., Krata P.

Journal of Theoretical and Applied Mechanics

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2016

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Vol. 54 nr 4

1329--1343

EN

The paper deals with the problem of prediction of the rolling period. A special emphasis is put on the practical application of the new method for rolling period prediction with regard to non-linearity of the GZ curve. The one degree-of-freedom rolling equation is applied with using the non-linear stiffness moment and linear damping moment formulas. A number of ships are considered to research the discrepancies between the pending GM-based IMO- -recommended method and the results of conducted numerical simulations performed for a wide range of operational loading conditions. Since the research shows some drawbacks of the IMO formula for the ship rolling period, a new formula is worked out and proposed instead.

8

Virtual ship’s roll decay test with the use of CFD technique

Krata P., Jachowski J.

Journal of KONES

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2016

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Vol. 23, No. 2

215--221

EN

Since safety of navigation is related to the stability performance of a ship, the transverse stability is routinely calculated and measured. One of the crucial experimental approach is a roll decay test. Although, an obtained result of the roll decay test carried out on the full-scale ship needs to be compared to a benchmark enabling an estimation of the relevant stability. Nowadays such a benchmark is just based on the simplified GM-based IMO-recommended formula. This research aims at the more sophisticated method of ship’s natural period of roll estimation and thus her stability assessment. The CFD (computational fluid dynamics) technique is applied and the result of the free roll simulation is compared to the solution of a roll equation. The one degree-of-freedom roll equation is applied with regard to the nonlinear ship righting moment and the nonlinear damping moment obtained according to Ikeda’s method. The six degrees-of-freedom simulation of ship’s roll decay test was carried out by the use of FlowVision code utilizing the Reynolds-averaged Navier–Stokes equation with regard to the turbulent flows based on the eddy viscosity concept. The semi-empirical k-ε turbulence model was applied. Thereby, the CFD-based approach allows to get rid of any assumptions regarding the value of the damping coefficient, which is an advantage over the roll equation based approach.

9

Prediction of the natural frequency of ship’s roll with regard to various models of roll damping

Krata P., Wawrzyński W.

Journal of KONES

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2016

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Vol. 23, No. 3

289--296

EN

One of the most important dynamic phenomenon recognized as dangerous to seagoing ships is the resonance gain of rolling. This may occur due to nonlinearity of ship response in resonance conditions, i.e. when the encounter wave frequency is similar to the natural frequency of ship roll motion. Such coincidence should be avoided therefore shipmaster steers clear of some configurations of speed and course resulting in potential synchronous rolling. Nowadays, according to the IMO Intact Stability Code the natural period of roll is determined with the use of very simplified GM-based formula. The paper deals with the problem of more sophisticated prediction of ship’s natural rolling frequency with the use of the one degree-of-freedom roll equation with regard to nonlinear restoring moment. A special emphasis is put on the damping coefficient modelling which remains one of the crucial issues in terms of rolling simulation. Two typical approaches to the damping coefficient estimation are tested, the linear and the nonlinear one according to Ikead’s method. The set of ship roll simulations is carried out for a wide range of excitation frequency and a variety of exciting moment. The results of computation focused on the natural frequency of ship roll prediction are compared to assess the influence of damping model selection.

10

Szacowanie okresu kołysań własnych statków kontenerowych : porównanie metody uproszczonej z wynikami badań symulacyjnych

Krata P., Wawrzyński W.

Autobusy : technika, eksploatacja, systemy transportowe

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2016

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R. 17, nr 4

72--77

PL

Artykuł przedstawia porównanie wartości okresu kołysań swobodnych statku wyznaczonego na podstawie wzorów uproszczonych zalecanych przez IMO w Kodeksie Stateczności Statku Nieuszkodzonego oraz uzyskanych w toku przeprowadzonych symulacji numerycznych. Do wykonania analizy wykorzystano dane trzech statków kontenerowych różnej wielkości i różnej generacji. Przyjęto po cztery typowe stany załadowania dla każdego ze statków. Wyniki porównania zestawiono na wykresach okresu kołysań w funkcji amplitudy dla szerokiego zakresu amplitud kołysania bocznego.

EN

The paper deals with the matter of estimation of ship’s free rolling period. The comparison of calculations based on the IMO-recommended method versus numerical simulations is presented. The particulars of three container vessels of different sizes and generation were used to perform simulations of their free rolling. Four typical loading conditions of each ship were taken into account. The results of comparison are presented in the form of plots presenting obtained rolling periods versus rolling amplitude for a wide range of such amplitude of ship rolling.

11

Modelowanie CFD osiadania statków kontenerowych podczas manewru wymijania na torze wodnym

Jachowski J., Krata P.

Autobusy : technika, eksploatacja, systemy transportowe

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2016

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R. 17, nr 4

64--71

PL

W artykule omówiono badania nad zastosowaniem zaawansowanych obliczeń numerycznej mechaniki płynów do wyznaczania trajektorii ruchu (w sześciu stopniach swobody) statku morskiego żeglującego na akwenie ograniczonym podczas manewru wymijania z innym statkiem. Uwzględniono jednocześnie zarówno oddziaływanie dna i brzegów kanału o zadanej geometrii jak również oddziaływanie wymijanego statku, co jest podejściem nowatorskim na skalę światową. Wyniki symulacji przeanalizowano pod wzglądem hydrodynamicznego zjawiska osiadania, powstającego podczas przejścia statku przez akwen ograniczony głębokością i brzegami kanału przy jednoczesnej interakcji z wymijanym statkiem. W obliczeniach wykorzystano geometrię typowego statku kontenerowego.

EN

Paper describes a research into ship’s squat phenomenon which is related to the safe entering of large ships into contemporary existing sea harbors. As the significant research effort in ship hydromechanics is devoted in recent years to the practical navigation problems, the Authors follow this trend and addressed the squat by means of CFD numerical simulations. The analysis of 6 DOF ship motion was performed, including the effects of shallow water, horizontal restrictions, extend of a channel and especially ship squat during passing by maneuver at a waterway. An exemplary case-study is carried out for a large container vessel. The obtained results were experimentally verified by comparison to one German experiment and own models tests. Such complex approach is a novelty worldwide.

12

Variations of Ship’s Deck Elevation Due to Stochastic Process of Containers Loading

Krata P.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2015

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Vol. 9, no. 4

467--473

EN

The stochastic process of container loading is described in the paper with special emphasis to ship motion when she is lying at a quay. The 3 DOF system was applied to describe rolling, pitching and heaving of a vessel which may cause a significant variations of momentary deck elevation. The realistic range of such variations are assessed for a variety of cargo locations on-board and a phase shift between two independent gantries engaged in cargo operations. The process is modeled with regard to random character of crucial variables affecting ship motion due to cargo loading.

13

Ocena możliwości modyfikacji parametrów statecznościowych statków morskich w świetle danych statystycznych o rzeczywistych stanach załadowania kontenerowców

Krata P.

Logistyka

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2015

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nr 3

2447--2456, CD 1

PL

W artykule omówiono stosowane współcześnie miary stateczności poprzecznej statków morskich oraz zasady normowania tej stateczności zawarte w Kodeksie stateczności statku nieuszkodzonego. Następnie zaproponowano koncepcję wprowadzania modyfikacji parametrów statecznościowych w celu zwiększenia bezpieczeństwa żeglugi. Ideą jest dostosowywanie aktualnej stateczności statku do warunków hydrometeorologicznych dla uniknięcia wejścia w strefę rezonansu kołysań bocznych. Zaprezentowano możliwość wpływania na położenie tej strefy poprzez zmianę wartości wysokości metacentrycznej statku. Jako że położenie strefy rezonansowej jest uzależnione od wzajemnej relacji okresu spotkaniowego fali i okresu kołysań własnych statku, ten drugi może być modyfikowany poprzez zmianę wartości wysokości metacentrycznej i tym samym relokację niebezpiecznej strefy. Wzrost wartości GMp jest w praktyce trudny do uzyskania, jednak obniżenie tej wartości jest wykonalne. Warunkiem koniecznym jest jednak posiadanie odpowiedniego zapasu stateczności, stąd wykonano analizę raportowanych z wielu statków kontenerowych stanów załadowania. Wykazała ona znaczne przekroczenie minimalnych wymagań statecznościowych, co daje możliwość zastosowania w praktyce proponowanego rozwiązania.

EN

The contemporary approach towards ship stability determination is described in the paper, as well as the proscriptive stability standards contained in the International Code on Intact Stability. Then the concept of modification of ship stability characteristics is introduced, aiming at an increase in safety of navigation. The core idea of the proposal consists in an adjustment of ship stability parameters to the contemporary hydro-meteorological conditions to avoid entering a synchronous rolling zone. The possibility of relative shift of this dangerous zone is described and demonstrated on the basis of a sample calculations. As its location depends on the relation between wave encountering period and ship rolling period, the latter one may be adjusted by tuning of the metacentric height. Such modifications of ship stability parameters are relatively difficult in terms of an increase in metacentric height but practically feasible by decreasing of it. Thus, the realistic range of stability parameters of container vessels is analyzed. The reported loading conditions in a wide group of container vessels correspond to the much better stability characteristics then required by the ISC standards, which enables proposed modifications. The study reveals the feasibility of an application of the main concept.

14

Assessment of a critical area for a give-way ship in a collision encounter

Krata P., Montewka J.

Archives of Transport

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2015

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Vol. 34, iss. 2

51--60

EN

Evasive action in ship-ship encounter has to be carried out on time and in line with the international convention on collision regulation – COLREG. The convention not only includes a set of rules defining types of relations between encountering ships but also indicates appropriate action to be taken in a given encounter. One of such encounters is crossing, where, in case of a collision situation, a give-way ship has to take an appropriate action in due time. However, a stand-on vessel is also given an opportunity to manoeuver, if it is made clear to her that the other ship is not fulfilling her obligations. However, it is difficult to specify, at which point in time in the course of an encounter, the stand-on ship has to take an action in order to avoid collision. It is understandable, as this parameter depends on numerous factors, both endogenous (e.g. ship characteristics, her maneuverability), and exogenous (e.g. type of encounter, weather conditions). Therefore in this paper we make an attempt towards the definition of the critical area for a maneuver of a stand-on ship, in the situation where the give-way vessel does not take an action. This is determined with the use of a hydrodynamic model of ship motion, and series of simulations conducted for several types of encountering ships under various conditions. Once determined, the critical area demarcates the no-go area around the own ship, where any other ships on collision courses must not enter. Otherwise a collision cannot be avoided by an action of one ship alone.

15

A Method of Assessment of the Liquid Sloshing Impact on Ship Transverse Stability

Krata P.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2014

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Vol. 8 no. 4

535--541

EN

Liquid sloshing phenomenon taking place in partly filled ships’ tanks directly affects the stability of a vessel. However, only static calculations are carried out onboard ships nowadays and static transfer of liquid weight is taken into account in the course of routine stability calculation. The paper is focused on a dynamic heeling moment due to liquid sloshing in tanks onboard ships. The set of numerical simulations of liquid sloshing taking place in moving tanks is carried out. The realistic range of geometric parameters is taken into account. The conducted CFD simulations are experimentally verified. Finally, the method of an assessment of the liquid sloshing impact on ship transverse stability is worked out. The key point of the method is a dynamic coefficient describing relation of the researched dynamic heeling moment and the quasi-static one in terms of dynamic stability of a vessel which is related to the weather criterion of ship stability assessment.

16

Zastosowanie numerycznej mechaniki płynów do prognozowania osiadania statku na torze wodnym o zmiennej geometrii

Jachowski J., Krata P.

Logistyka

|

2014

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nr 3

2414--2424

PL

W niniejszym artykule omówiono badania nad zastosowaniem zaawansowanych obliczeń numerycznej mechaniki płynów prowadzące do wypracowania metody obliczeniowej, która pozwoli wyznaczać osiadanie statków o dowolnym kształcie podwodnej części kadłuba, poruszających się na akwenie o dowolnym ukształtowaniu dna i brzegów. Za przykładowy akwen wybrano tor podejściowy do Portu Świnoujście na którym zamodelowano ruchu statku w sześciu stopniach swobody. Wyniki symulacji przeanalizowano pod wzglądem hydrodynamicznego zjawiska osiadania, powstającego podczas przejścia statku przez akwen ograniczony głębokością i brzegami kanału.

EN

In the recent years a significant research effort in ship hydromechanics is devoted to the practical navigation problems and among them one of the most crucial which is safe entering of large ships into contemporary existing sea harbors. The analysis of such ship motion could include the effects of shallow water, horizontal restrictions, asymmetric channels, ship squat, ship to ship interactions etc. The paper presents the attempt to determine the ship squat at waterway using the computational fluid dynamics (CFD) simulations with implemented six degree-of-freedom ship motion model and a realistic sea bottom profile. A case study was carried out for the Świnoujście harbor waterway. The obtained results of performed simulations were analyzed with regard to ship squat as an element of safe under keel clearance in such restricted area.

17

The Impact of Sloshing Liquids on Ship Stability for Various Dimensions of Partly Filled Tanks

Krata P.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

|

2013

|

Vol. 7, no. 4

481--489

EN

Liquid sloshing phenomenon taking place in partly filled ships’ tanks directly affects the stability of a vessel. However, only static calculations are carried out onboard ships nowadays and static transfer of liquid weight is taken into account in the course of routine stability calculation. The paper is focused on a dynamic heeling moment due to liquid sloshing in tanks onboard ships. A number of numerical simulations of liquid sloshing taking place in a moving tank is carried out. The wide range of ship’s tanks is taken into account. The conducted CFD simulations are experimentally verified. Finally, the method of an assessment of the liquid sloshing impact on ship transverse stability is worked out. The key point of the method is a dynamic coefficient describing relation of the researched dynamic heeling moment and the quasi-static one in terms of dynamic stability of a vessel which is related to the weather criterion of ship stability assessment.

18

Dynamika ruchu cieczy ze swobodną powierzchnią w ocenie stateczności statku morskiego

Krata P., Jachowski J., Wawrzyński W.

Prace Naukowe Politechniki Warszawskiej. Transport

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2013

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z. 98

331--343

PL

Przedmiotem badań opisanych w artykule jest ruch cieczy w niepełnych zbiornikach okrętowych w kontekście jego wpływu na stateczność statku w stanie nieuszkodzonym. Badania nakierowane były na efekty dynamiczne występujące w zbiorniku podczas kołysania statku na fali, co jest dotychczas pomijane w procedurze oceny stateczności statku wykonywanej przez oficera ładunkowego, która wynika z zaleceń Międzynarodowej Organizacji Morskiej. W toku badań wzięto pod uwagę zarówno geometrię typowych zbiorników okrętowych jak również realistyczne charakterystyki wymuszenia ruchu zbiorników wynikającego z kołysania bocznego statku. Przeprowadzono zarówno analizę istniejących rozwiązań konstrukcyjnych statków morskich jak i badania eksperckie w zakresie stanów eksploatacyjnych statków towarowych. Zaproponowano metodę porównania dynamicznego momentu od przelewającej się w zbiorniku cieczy z momentem obliczonym na podstawie poprawki na swobodne powierzchnie cieczy. Na podstawie zweryfikowanych eksperymentalnie badań symulacyjnych wskazano na możliwość niedoszacowania wpływu swobodnych powierzchni cieczy w toku obliczeń zgodnych z zalecaną procedurą IMO.

EN

The main subject of the conducted study is liquid sloshing phenomenon taking place in partly filled ship tanks. The effects of this phenomenon influencing intact ship transverse stability are considered in terms of the heeling moment due to liquid sloshing. The research was focused on the dynamic effects playing an important role since the ship rolls on waves. The special attention was put on the stormy conditions emerging in the research in the form of high amplitudes of ship's rolling. Such dynamic effects are omitted in the contemporary procedure of ship stability assessment performed according to the IMO recommendations. The number of characteristics was taken into account in the course of the research. The rolling periods and amplitudes were established as well as tanks geometry and location in ship’s hull. Numerous ships were analyzed and the expert’s pool was conducted to estimate extreme but realistic rolling amplitudes. A method for comparison of dynamic heeling moment due to liquid sloshing and quasi-static heeling moment was proposed. An exemplary result of computation, revealing a significant underestimation of free surface effect was presented.

19

Ship’s ballast tanks size and dimensions review for the purpose of model research into the liquid sloshing phenomenon

Krata P., Wawrzyński. W., Więckiewicz W., Jachowski J.

Zeszyty Naukowe / Akademia Morska w Szczecinie

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2012

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nr 29 (101)

88-94

EN

The paper presents the pending stage of a study into the influence of liquid sloshing phenomenon taking place in ships’ tanks on ship transverse stability. The research is carried out at the Gdynia Maritime Academy and it comprises both numerical simulations and experimental test. A number of problems needs to be addressed and one of them is proper planning of geometry of a model tank utilized in the course of experimental tests. It shall refer to the real ships’ tanks shapes to model liquid sloshing phenomenon fair enough. The typical groups of ships’ tanks are analyzed and presented as well as the free surface correction effecting vessels’ transverse stability.

PL

W artykule przedstawiono element prowadzonego projektu badawczego dotyczącego wpływu zjawiska sloshingu zachodzącego w niepełnych zbiornikach okrętowych na stateczność poprzeczną statku morskiego. Badania realizowane w Akademii Morskiej w Gdyni obejmują zarówno symulacje numeryczne, jak i nieodzowne badania eksperymentalne. Jednym z zagadnień jest zaprojektowanie zbiornika modelowego wykorzystywanego w eksperymencie, który winien prawidłowo odzwierciedlać kształty i proporcje zbiorników okrętowych. Poddano zatem analizie populację statków morskich i ich zbiorników balastowych, wyróżniając charakterystyczne cechy tych zbiorników, w tym poprawkę od swobodnych powierzchni cieczy.

20

Computing of momentary ship’s deck elevation for the purpose of gantry control during cargo handling operations in sea ports

Krata P., Szpytko J., Weintrit A.

Zeszyty Naukowe / Akademia Morska w Szczecinie

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2012

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nr 29 (101)

81-87

EN

The paper presents a proposal of a method for the computation of ship’s deck elevation at any time and location on-board. The need for such a computation results from an interaction between a ship and cargo being loaded or discharged by a gantry in port, in terms of heeling and rolling of the vessel. The main purpose of such modeling is the need for improvement of gantry control with regard to faster operations thanks to more accurate estimation of level and moment of cargo release from a gantry hook or spreader. The study may be the contribution to the development of gantry control systems in sea ports.

PL

W artykule przedstawiono propozycję metody obliczania chwilowego wzniosu pokładu statku podczas operacji ładunkowych w porcie. Potrzeba prowadzenia takich obliczeń wynika ze wzajemnego oddziaływania ładowanego ładunku na statek i odpowiednio – statku na proces załadunku. Statek doznaje bowiem zmiennego w czasie przechyłu wskutek umieszczenia na pokładzie bądź w ładowni dowolnej masy, np. kontenera. Zasadniczym celem opisywanych obliczeń jest poprawa dokładności sterowania suwnicą kontenerową poprzez wyznaczenie chwilowego poziomu pokładu w miejscu przeznaczenia każdego ładowanego kontenera i dalej – precyzyjne określenie wysokości i momentu ustawienia kontenera. Przeprowadzone badania mogą się przyczynić do rozwoju systemu sterowania suwnicami w portach morskich.